Inkjet printing ink

Abstract

An inkjet printing ink having properties of crosslinking and being fixed on a fiber by heating, characterized in that in an ink composition consisting of (A) a pigment dispersion having a mean particle diameter of 200 nm or less and a maximum particle diameter of 500 nm or less, consisting of a pigment, a water-soluble pigment dispersant and a hydrophilic solvent, (B) a water-soluble fixing agent, and (C) a crosslinking agent, the water-soluble pigment dispersant in (A) is a specific emulsion polymer neutralized by a basic substance; the water-soluble fixing agent (B) is the one having a crosslinking functional group; and the crosslinking agent (C) is the one having a functional group that crosslinks the crosslinking functional group of the water-soluble pigment dispersant in (A) with the crosslinking functional group of the water-soluble fixing agent (B) at a temperature of 100° C. or more.

What is claimed is: 
     
       1. An inkjet printing ink comprising
 (A) a pigment dispersion having a mean particle diameter of 200 nm or less and a maximum particle size of 500 nm or less, consisting of a pigment, a water-soluble pigment dispersant, and a hydrophilic solvent, 
 (B) a water-soluble fixing agent, and 
 (C) a crosslinking agent, and having properties of crosslinking and being fixed on a fiber by heating, wherein 
 the water-soluble pigment dispersant in (A) is an emulsion polymer having a molecular weight of 2,000-20,000 consisting of (1) 20-80 parts of (meth)acrylic acid ester monomer represented by CH 2 ═CR 1 —COOR 2  (wherein R 1  denotes a hydrogen atom or a methyl group, R 2  denotes an alkyl group with a carbon number of 2-8), (2) 80-20 parts of an aliphatic vinyl monomer comprising a carboxyl group, and (3) 0-20 parts of an aliphatic vinyl monomer comprising a non-carboxylic crosslinking functional group, which is neutralized by a basic substance; 
 the water-soluble fixing agent (B) comprises a crosslinking functional group; and 
 the crosslinking agent (C) comprises a functional group that crosslinks the crosslinking functional group of the water-soluble pigment dispersant in (A) and the crosslinking functional group of the water-soluble fixing agent (B) at a temperature of 100° C. or more. 
 
     
     
       2. The inkjet printing ink according to  claim 1 , wherein the emulsion polymer used for the water-soluble pigment dispersant in (A) has been polymerized under the presence of a reactive surfactant. 
     
     
       3. The inkjet printing ink according to  claim 1 , wherein the aliphatic vinyl monomer (2) comprising a carboxyl group of the water-soluble pigment dispersant in (A) is one or more selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid. 
     
     
       4. The inkjet printing ink according to  claim 1 , wherein a secondary amine or a tertiary amine is used as the basic substance for neutralizing the emulsion polymer with a molecular weight of 2,000-20,000 that constitutes the water-soluble pigment dispersant in (A). 
     
     
       5. The inkjet printing ink according to  claim 1 , wherein the amount of blending of the water-soluble pigment dispersant in (A) is 5-40 mg per 1 m 2  of surface area of the pigment. 
     
     
       6. The inkjet printing ink according to  claim 1 , wherein a polyoxyethylene styrenated phenyl ether sulfate or a polyoxyethylene alkyl ether sulfate is used as an aid of dispersing ability of the water-soluble pigment dispersant in (A). 
     
     
       7. The inkjet printing ink according to  claim 1 , wherein the ratio of the blending amounts of the pigment to the water-soluble pigment dispersant in (A) is 1:0.1-2.0. 
     
     
       8. The inkjet printing ink according to  claim 1 , wherein the water-soluble fixing agent (B) is one or more selected from the group consisting of water-soluble urethane resin, water-soluble epoxy resin, water-soluble acrylic resin, and modified polyvinyl alcohol (PVA). 
     
     
       9. The inkjet printing ink according to  claim 8 , wherein the glass transition point (Tg) of the water-soluble fixing agent (B) is in the range between −60° C. and 20° C. 
     
     
       10. The inkjet printing ink according to  claim 8 , wherein the water-soluble urethane resin as the water-soluble fixing agent (B) comprises a carboxyl group and a hydroxyl group which function as both a crosslinking functional group and a hydrophilic group, and has an acid number of 20-90 mg KOH/g and a hydroxyl number of 20-70 mg KOH/g. 
     
     
       11. The inkjet printing ink according to  claim 1 , wherein a hot melt resin with a maximum particle diameter of 500 nm or less is used as an aid of fixing ability of the water-soluble fixing agent (B). 
     
     
       12. The inkjet printing ink according to  claim 1 , wherein a water-soluble or self-emulsifying crosslinking agent is used as the crosslinking agent (C) to obtain a property of excellent re-dispersibility. 
     
     
       13. The inkjet printing ink according to  claim 1 , wherein the crosslinking agent (C) is a blocked isocyanate compound in which a trimethylol propane (TMP) adduct or isocyanurate of hexamethylene diisocyanate (HDI), hydrogenated xylene diisocyanate (H6XDI), isophorone diisocyanate (IPDI) or dicyclohexylmethane diisocyanate (H12MDI) as an isocyanate is blocked. 
     
     
       14. The inkjet printing ink according to  claim 13 , wherein the crosslinking agent (C) is a blocked isocyanate compound which is blocked by diethyl malonate (DEM), diisopropyl amine (DIPA), 1,2,4-triazol (TRIA), 3,5-dimethylpyrazol (DMP) or 2-butanone oxime (MEKO) as a blocking agent. 
     
     
       15. The inkjet printing ink according to  claim 1 , wherein the viscosity is in the range of 3-15 mPa·s at 20° C. 
     
     
       16. The inkjet printing ink according to  claim 1 , wherein the surface tension is in the range of 27-38 mN/m. 
     
     
       17. The inkjet printing ink according to  claim 1 , wherein large pigment particles of 500 nm or more are filtered off and separated by a filter or centrifugation. 
     
     
       18. An inkjet printing method comprising:
 printing a fiber with the inkjet printing ink according to  claim 1  by inkjet system, and 
 heat-treating the fiber at a temperature of 100° C. or more. 
 
     
     
       19. The inkjet printing method according to  claim 18 , wherein the fiber is pretreated with a cationic compound by a padding method, a coating method, a screen printing method, a spraying method or an inkjet method. 
     
     
       20. The inkjet printing method according to  claim 19 , wherein the fiber is pretreated with one or more selected from the group consisting of a urethane resin emulsion, an acrylic resin emulsion and a crosslinking agent, in addition to the cationic compound. 
     
     
       21. The inkjet printing method according to  claim 18 , wherein the fiber is post-treated with a post-treatment agent by a padding method, a coating method, a screen printing method, a spraying method or an inkjet method. 
     
     
       22. The inkjet printing method according to  claim 21 , wherein the post-treatment agent is one or more selected from the group consisting of an acrylic resin emulsion, a urethane resin emulsion, a silicone oil, a plasticizer, and a crosslinking agent. 
     
     
       23. A fiber printed by the inkjet printing method according to  claim 18 .